(1) Field of the Invention
This invention relates to pesticidal compositions such as insecticide, germicide, repellents and herbicide which are used for repelling or killing noxious organisms. In other words, the term "pesticidal composition" includes the composition that keeps noxious organisms away or kills them to prevent their attack.
(2) Description of Prior Art
The pesticidal composition to noxious organisms such as agricultural chemicals are used in various forms of preparations. The forms of compositions are exemplified by solid forms such as powder, powdery granules, granules, hydrated preparations and pills; liquid forms such as solutions, emulsions, oily preparations and flowable preparations; and aerosols, coating compositions, gaseous agents, smoking agents and microcapsules. In a microcapsule-type preparation, an effective component is encapsulated with a high polymer membrane or thin sheets of effective component are sandwiched between layers of polymer.
More particularly, the powdery composition is prepared through a process such that an effective component is mixed with powder of clay mineral such as talc or bentonite, and the mixture is then pulverized into fine powder of about 10 .mu.m in average diameter. This can be used intact by spreading with a sprayer. The DL powder in which the drifting is minimized by removing very fine powder having a particle size smaller than a certain value and flow dust (FD) composition for use in gardening fall under the above-mentioned category. The powdery granules are prepared by using clay powder which has a particle size larger than that of the above powdery composition. The granular composition is a solid preparation of medium-sized particles of a value between those of the above powdery composition and the powdery granules.
The hydrated composition is prepared by adding a clay mineral, surface active agent and diluent to an effective component which is hardly soluble to water, thereby forming a powdery solid. When this composition is used, a suitable quantity of water is added to prepare a suspension and the prepared suspension is sprayed. Further-more, exemplified as the compositions belonging to this category are the hydrated tablets (dry flowable pills) having a larger particle size and a water soluble composition which is prepared by adding an auxiliary component to a water soluble effective component.
The liquid composition is a concentrated solution of an effective component which is prepared by dissolving the effective component into a suitable volatile solvent. The liquid composition is also exemplified by an emulsion and an oily composition. The emulsion is prepared by emulsifying an effective component in water or in an organic solvent with a surface active agent. The oily composition is prepared by dissolving an effective component into an organic solvent. Both of them can be used by diluting with water or with an organic solvent and then spraying or spreading.
The constituents of the above compositions are generally classified into three groups of effective components (chemical agents for killing or repelling noxious organisms), diluents and auxiliary agents. The effective components are the so-called agricultural chemicals. The diluent facilitates the preparation of the pesticidal composition by diluting the effective component properly. The diluents are exemplified by solid diluents (carriers) and liquid diluents. The auxiliary agents are used for imparting several properties such as emulsifiability, dispersibility, spreadability and solubility relative to the effective component, for preventing the effective component from decomposition during storage or after spraying, or for improving the sticking of effective component to farm products. Even when the auxiliary agent itself has no pesticidal effect, those which can enhance the effect of the composition when used together are also included in the category of auxiliary agent. By the way, it is sometimes difficult to distinguish the above-mentioned diluents from the auxiliary agents.
The preparation of pesticidal composition using the liquid diluent or auxiliary agent will be described further.
In the preparation of an oily composition, they are employed as an organic solvent to dissolve the effective component. In the preparation of emulsified composition, a solution of effective component is formed and the solution is emulsified with water. In the case of powder composition and granular composition, an effective component is dissolved in a solvent and carrier particles are coated with the solution or the carrier is kneaded or impregnated with the solution so as to form powder or granular composition.
The organic solvents used for preparing the oily composition and emulsified composition are exemplified by the hitherto used hydrocarbons such as alcohols, ketones, ethers and paraffins; and aromatic hydrocarbons such as benzene, toluene, xylene and dodecylbenzene. Besides these solvents, there are proposed the use of phenyl xylylethane (Japanese Patent Publication No. Sho 56-19841) and compounds having specific structure (Japanese Patent Publication No. Sho 58-14401).
Furthermore, the uses in the preparation of solid compositions are disclosed in U.S. Pat. No. 4,760,084; U.S. Pat. No. 4,871,766 and U.S. Pat. No. 4,886,656.
It is to be noted, however, that the spreading or spraying using phenyl xylylethane as disclosed in Japanese Patent Publication No. Sho 56-19841 is not satisfactory in view of the safety to fire. In order to ensure the safety, the substance having a higher flash point and higher boiling point is desired.
Also concerning the smell, with giving consideration to worker's unpleasant feeling in the spreading or spraying operation, odorless composition having no nasty smell is required. When the pesticidal composition in any form is used to noxious organisms, it is spread or sprayed in large quantities over fields, farms, fruit farms, forests, lumber, houses and so forth. Therefore, it is necessary to use odorless composition in view of the prevention of environmental pollution.